Experimental Validation of a Scaling Law for the Critical Current of Commercial REBCO Tapes as a Function of Magnetic Field and Temperature

Much information is lacking at present on the electrical properties of commercial REBCO tapes. This work, which builds on a previous paper of the same authors, presents the results of an experimental campaign aimed at deriving the critical current of tapes from SuperPower, Fujikura, Faraday Factory, and Shanghai Superconductor Technology. The campaign was conducted by applying both the transport method at 4.2 K, in perpendicular background magnetic fields of up to 15 T, and the magnetization method from 4.2 K up to the critical temperature in fields of up to 10 T. This latter method was adopted to determining the so-called crossover field, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{B}_0}$</tex-math></inline-formula>, at which the transition from single vortex pinning to collective pinning takes place. <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{B}_0}$</tex-math></inline-formula> is challenging to determine by the transport method because of the high currents involved (at 4.2 K, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{B}_0}$</tex-math></inline-formula> is roughly 1 T, which corresponds to currents above 1500 A, for a 4 mm tape). Magnetization measurements corroborate transport measurements at 4.2 K both below <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{B}_0}$</tex-math></inline-formula> and up to 10 T. Further magnetization measurements above 4.2 K allow the temperature dependence of the scaling parameters to be derived, for correlation with the methodology of flux pinning enhancement by different manufacturers. This provides insights about the effectiveness and interplay of pinning mechanisms.